Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
64 results
Search Results
Item Numerical simulation of viscous flow past elliptic cylinder(Pleiades journals, 2019) Maniyeri, R.A study on flow over bluff bodies is a prime research problem in mechanical engineering since it helps to understand various fluid dynamics characteristics. This is a fluid–structure interaction problem which makes it challenging and complex. This paper discusses the development of a computational model to simulate the viscous flow over an elliptic cylinder. In this paper, a feedback forcing-based immersed boundary method coupled with Dirac delta function is used to construct the model. Also, two coordinates systems are employed—Lagrangian (for elliptic cylinder) and Eulerian (for fluid flow). Initially, the developed numerical model is validated. Later, the flow behavior for a fixed aspect ratio of the elliptic cylinder is studied for different Reynolds numbers. It can be seen that steady symmetric flow pattern is obtained for the range of Reynolds numbers considered in the present study. © Springer Nature Singapore Pte Ltd. 2019.Item Numerical study on the dynamics of organism motion under background flow(Association for Computing Machinery acmhelp@acm.org, 2017) Maniyeri, R.; Kang, S.We propose a two-dimensional numerical model to investigate the dynamic behaviour of an organism swimming in a background flow in a channel. In this work, the organism is modeled as a neutrally buoyant one-dimensional elastic filament based on an immersed boundary finite volume method. Further, the organism is modeled using discrete number of immersed boundary points and the Navier-Stokes equations governing the flow are solved on a staggered Cartesian grid system. A driving function is applied which results in a wave travelling along the length of the organism from left to right. It is found that under no background flow, the organism swim in the forward direction (right to left) when the wave travel over the organism is in the opposite direction. It is observed that, under a uniform background flow, a non-motile organism is simply dragged by the flow whereas a motile organism swims backward along the direction of flow. Further, it is seen that a propulsion enhancement is found in the case of organism swimming along the flow direction when the wave travel is in the opposite direction as that of the flow. © 2017 Association for Computing Machinery.Item Numerical analysis of mixed convection in a lid-driven cavity with Cu-water nanofluid using artificial compressibility method(Dalian University of Technology, 2018) Katti, A.S.; Maniyeri, R.In this paper, we present a computational model based on an artificial compressibility method to study mixed convection in a lid-driven square cavity containing Cu-water nanofluid for two cases: i) adiabatic vertical walls and horizontal walls kept at constant temperature, and ii) adiabatic horizontal walls and sinusoidal temperature heating along vertical walls. The artificial compressibility method is used to couple pressure and velocity, and solve the momentum and continuity equations. This method is used because of its simplicity in solving steady state incompressible flow problems. The streamlines, isotherms, variation of local Nusselt number at hot walls, and variation of average Nusselt number with change in Cu-nanoparticle concentration are presented. Also, the variation of local Nusselt number with change in Richardson number (0.1 < Ri < 10), keeping Grashof number constant (Gr = 100), is obtained. For both cases, it is found that heat transfer increases with increase in Cu-nanoparticle concentration, keeping Richardson number constant, and also with a decrease in Richardson number, keeping Grashof number constant. © 2018 by the authors of the abstracts.Item Flow analysis for efficient design of wavy structured microchannel mixing devices(American Institute of Physics Inc. subs@aip.org, 2018) Kanchan, M.; Maniyeri, R.Microfluidics is a rapidly growing field of applied research which is strongly driven by demands of bio-technology and medical innovation. Lab-on-chip (LOC) is one such application which deals with integrating bio-laboratory on micro-channel based single fluidic chip. Since fluid flow in such devices is restricted to laminar regime, designing an efficient passive modulator to induce chaotic mixing for such diffusion based flow is a major challenge. In the present work two-dimensional numerical simulation of viscous incompressible flow is carried out using immersed boundary method (IBM) to obtain an efficient design for wavy structured micro-channel mixing devices. The continuity and Navier-Stokes equations governing the flow are solved by fractional step based finite volume method on a staggered Cartesian grid system. IBM uses Eulerian co-ordinates to describe fluid flow and Lagrangian co-ordinates to describe solid boundary. Dirac delta function is used to couple both these co-ordinate variables. A tether forcing term is used to impose the no-slip boundary condition on the wavy structure and fluid interface. Fluid flow analysis by varying Reynolds number is carried out for four wavy structure models and one straight line model. By analyzing fluid accumulation zones and flow velocities, it can be concluded that straight line structure performs better mixing for low Reynolds number and Model 2 for higher Reynolds number. Thus wavy structures can be incorporated in micro-channels to improve mixing efficiency. © 2018 Author(s).Item Computational study of fluid flow in wavy channels using immersed boundary method(Springer Verlag, 2019) Kanchan, M.; Maniyeri, R.Accurate control and handling of fluids in microfluidic-based bio-medical devices is very important in diverse range of applications such as laboratory-on-chip (LOC), drug delivery, and bio-technology. Flow through medical devices such as kidney dialyzer and membrane oxygenator can be considered as laminar due to low Reynolds number and narrow channel geometry, thus requiring efficient utilization of passive modulation systems to improve fluid mixing in these devices. In the present work, numerical investigation of fluid flow and passive mixing effects is carried out for wavy-walled channel configurations. A two-dimensional computational model based on an immersed boundary finite volume method is developed to perform numerical simulation on a staggered Cartesian grid system. Further, pressure–velocity coupling of governing continuity and Navier–Stokes equations describing the fluid flow is done by SIMPLE algorithm. Fluid variables are described by Eulerian coordinates and solid boundary by Lagrangian coordinates. Linking of these coordinate variables is done using Dirac delta function. A momentum-forcing term is added to the Navier–Stokes equation in order to impose the no-slip boundary condition on the wavy wall. Parametric study is carried out to analyze the fluid flow characteristics by varying wave geometry factor (WG Factor) of crest–crest (CC Model) wavy wall configurations for Reynolds number ranging from 10 to 50. From this work, it is evident that incorporating wavy-walled passive modulators prove to be good and robust method for enhancing mixing in biomedical devices. © Springer Nature Singapore Pte Ltd. 2019.Item Modeling and Simulation of a Pedelec(Institute of Electrical and Electronics Engineers Inc., 2019) Thejasree, G.; Maniyeri, R.; Kulkami, P.This paper presents the mathematical model of an electric bike (e-bike) that was simulated in MATLAB/Simulink environment It discusses the individual elements, motor (permanent magnet synchronous motor), the controller(iield oriented control) and battery (lithium ion) associated with the e-bike system. The individual mathematical models are explained in detail. The dynamics associated with the vehicle system is also understood and applied to study the behavior of the system. The final pedelec model developed is with 4 assist levels. The simulation results obtained show that at different levels of assist the effort to be put in by the rider changes. This matches with the actual requirement, where the riders can use the bicycle for exercises purpose as well as get aid from the motor as and when required. © 2019 IEEE.Item E-bike system modeling and simulation(Institute of Electrical and Electronics Engineers Inc., 2019) Thejasree, G.; Maniyeri, R.A mathematical model of an electric bike (e-bike) developed in the MATLAB/Simulink environment is being discussed in this paper. The subsystem models, motor (permanent magnet synchronous motor), the controller(field oriented control) and battery (lithium ion) associated with the e-bike system has been separately detailed. Vehicle dynamics associated with the bicycle has also been studied to provide the required road reaction for correct simulation. The performance of the e-bike for two different slopes and different assist levels has been checked through simulation. The results show that the motor provides required assistance as set by the rider thereby providing both the advantages of exercise as well as extra aid from the motor. © 2019 IEEE.Item Numerical study on fluid flow through collapsible channels(Springer, 2020) Dhruv, V.; Mishra, U.; Maniyeri, R.The fluid flow in collapsible channels or tubes is an interesting problem with several physiological applications; for example, blood flow in veins, air flow in lungs and wheezing. In this paper, we present a fluid-structure interaction based model for single-phase fluid flow through a microchannel containing two elastic walls. A two-dimensional model is developed and simulations have been performed using a commercial software. The deforming geometry is analyzed using moving mesh. The flow field and deformation of the elastic walls for different boundary loads and inlet flow conditions are presented and discussed. © Springer Nature Singapore Pte Ltd. 2020.Item Numerical Study on the Behavior of an Elastic Capsule in Channel Flow Using Immersed Boundary Method(Springer Science and Business Media Deutschland GmbH, 2020) Maniyeri, R.; Kang, S.The study of motion and dynamic behavior of elastic capsules in Poiseuille flow in a channel has become an interesting topic of research because of the wide range of applications in the field of biomedical engineering. The behavior of an elastic capsule in an externally applied flow is challenging because of the large displacement fluid–elastic structure interaction involved. In this work, we develop a computational model to capture the physics of the motion and behavior of an elastic capsule in Poiseuille flow in a channel using an immersed boundary finite volume method. The circular-shaped capsule is divided into a number of immersed boundary (IB) points. We create elastic links structure between IB points to incorporate tension/compression and bending. The flow is governed by continuity and Navier–Stokes equations which are discretized using staggered grid-based finite volume method. Dirac delta function is used to interpolate between solid (capsule) and fluid grids. Simulations are first carried out to describe the instantaneous position and shape of the capsule at a fixed Reynolds number flow in the channel. It is observed that the initial location has a significant influence in determining the final shape and position of the capsule. Further, through numerical simulations, the position and shapes of circular capsule in center-line motion with different stiffness constants for links are obtained and compared. It is found that lower elastic spring constant together with lower bending stiffness constant leads to larger deformation of the capsule because of less resistance to the flow. Also, the outcome of different Reynolds numbers (Re) on the behavior of the capsule is investigated for the center-line motion. It is noticed that the motion of the capsule retards with the increase in Reynolds number. Also, for higher value of Re, the capsule deforms less. For lower value of Re, the capsule deforms to a large extent. © 2020, Springer Nature Singapore Pte Ltd.Item Numerical Analysis of Pulsating Flow in a Smooth Constriction Using Immersed Boundary Method(Springer Science and Business Media Deutschland GmbH, 2020) Kolke, D.K.; M, A.; Maniyeri, R.A major incentive for studying the flow of an incompressible fluid through a smooth constriction comes from the medical field. These constrictions represent arterial stenosis which is caused by deposition of intravascular plaques. To understand some of the major complications which can arise from arterial stenosis, the knowledge of the flow characteristics in the vicinity of constriction is essential. The main objective of the present work is to develop a two-dimensional computational model using a feedback forcing-based immersed boundary (IB) method to study steady and laminar pulsatile flow in a channel with a smooth constriction and investigate the effects of the Womersley number on the flow property. The study assumes the immersed boundary walls as rigid, and the flow is considered viscous, incompressible, and axisymmetric. The pulsatile flow simulations are done for a wide range of Womersley number within the physiological conditions for blood flow in arteries. The results obtained are in good agreement with the data from the literature. © 2020, Springer Nature Singapore Pte Ltd.